Anaerobic contactor

Abstract

In the treatment of high strength wastewater containing anaerobically digestible nutrients and organic substrates, the water is passed through a sealed reactor housing and the pressure in the headspace over the water is reduced under controlled conditions to provide for optimum operating conditions.

We claim: 
     
       1. A method of treating wastewater containing anaerobically digestable nutrients and substrates that include the steps of passing wastewater influent through a gas-tight reactor to establish a sealed headspace over the surface of the wastewater in said reactor,   rotating a plurality of partially immersed contactors through the wastewater contained in said reactor, each contactor having a biofilm thereon whereby the biofilm is sequentially passed through the wastewater and the headspace,   evacuating the atmosphere in the headspace to establish a subatmospheric pressure therein;   sensing the pressure in the headspace,   sensing the rate of flow of influent at the entrance to the reactor,   relating the sensed pressure to the sensed rate of flow of the influent to determine the chemical oxygen demand (COD) removal rate,   automatically adjusting the pressure in the headspace and the rate of flow of the influent to continually maintain the reactor at a desired operating condition.   
     
     
       2. The method of claim 1 wherein the chemical oxygen demand (COD) removal rate is determined for less than maximum removal by the relationship:   M.sub.R =M.sub.A C(1.084-0.48P)+k(16.24P-6.44)     where:   M R  is the mass of COD in g/m 2  /dy,   M A  is the mass of COD applied in g/m 2  /dy   C and k are both constants relating to the source characteristic of the influent, and   P is the headspace absolute pressure in atmospheres,   
     
     
       3. The method of claim 1 wherein the chemical oxygen demand (COD) removal rate is determined for maximum removal by the relationship:   M.sub.R =M.sub.A C(155.8-51.6P)     wherein:   M R  is the mass of COD removed in g/m 2  /dy,   M A  is the mass of COD applied in g/m 2  /dy,   C is a constant relating to the source characteristic of the wastewater,   P is the headspace absolute pressure in atmospheres.   
     
     
       4. The method of claim 1 that includes the further steps of partitioning the reactor into a plurality of sequential stages. 
     
     
       5. The method of claim 4 that includes the further step of mixing the influent before it passes into the first stage. 
     
     
       6. The method of claim 4 that includes the further step of adding additional influent to one or more selected stages.